Recoil mechanism for automatic firearms



RECOIL MECHANISM FOR AUTOMATIC FIREARMS Filed Oct. 5, 1944 2Sheets-Sheet 1 62-01%: lV/LLIHM Para/457T Aug. 26, 1%?

G. w. PATCHETT 2,4265%3 G'EORGEML Z MM PA TC HET T fll 'owaays,

Patented Aug. 26, 1947 RECOIL MECHANISM FOR AUTOMATIC FIREARMS GeorgeWilliam Patchett, Chigwell, England Application October 5, 1944, SerialNo. 557,293 In Great Britain April 1, 1943 This invention relates toimprovements in automatic firearms and has for its object the control ofthe recoiling bolt mass on the rearward and forward runs.

In automatic weapons to which the subject matter of this inventionrelates the operation of firing is dependent upon the movement of thebolt within its casing, said bolt having a shoulder formed in its lengthand in line with a trigger actuated sear, the latter engaging theshoulder for non-automatic operation, the sear, under a selection deviceof known type being held inoperative, and out of engagement with theshoulder when the weapon is desired to be automatic.

The bolt is caused to move rearward from the prior firing position bygas pressure of the explosive charge, this pressure and the energyimparted to the bolt being absorbed by a recoil spring.

In testing ammunition produced in various countries and of differing agethere is a very marked difierence in the amount of recoil of the boltand therefore the distance of the shoulder of the bolt beyond the searface. With a standard weapon of the type above described this differencemay vary in the movement of the bolt from a mean high travel of 1.87%inches to a low mean of 0.593 inch. Again on the same test there was adifference of 1.812 inches between the travel imparted by a poorammunition and a good ammunition when used in the same gun. Thisdifierence of possible travel of the bolt has many disadvantages. With ashort travel there is a risk that the shoulder is not engaged by thesear and that the automatic fire set up cannot be made to cease until astronger charge is fired or the magazine empty, If the travel is themaximum run of the bolt and of a high order the life of the weapon maybe impaired.

To avoid straining the firearm it is not permissible to fit a weakermain spring to compensate for the eiTect of weaker ammunition, and it isessential that the spring remains a standard to avoid separation of thearm into distinct classes for different makes of cartridges.

The invention enables a bolt of standard weight and a spring of standardstrength to be retained and wherein there is provided within the casingof the gun and at the rear of the bolt a braking device, which lattertends to absorb the surplus energy of the bolt movement with strongammunition, the said brake device being of a character progressively toretard movement but in a manner that admits, when the passage of thebolt is finally stopped, of the recoil spring reacting to urge the boltforward.

The invention consists in an automatic firearm of the type set forthwherein a resilient frictional braking device is adapted to operate incombination with the normal recoil spring to arrest bolt movement. Saidbraking device con- 1 Claim. (o1. 89198) sists of a continuous ordiscontinuous member concentric with or aligned to the said bolt, saidbraking device having outwardly flared tapering spring leaves. The boltis formed with a rear portion to engage the said braking device, or isprovided or fitted with a spring controlled sleeve having limitedmovement for a like purpose. The said braking device is characterisedthat its action to resist bolt motion becomes progressively greater asand when rearward motion continues, and is operative over equispacedparts of the peripheral contour of said bolt, and is preferably causedto be inoperative at or about cocking position of the said bolt.

Although the mechanical embodiment of the above invention may take morethan one form, the frictional braking device preferably consists of acylindrical sleeve which is split axially having an internal diameterslightly smaller than the outer diameter of a cylindrical sleeve mountedupon the bolt or a cylindrical portion of the bolt if the latter ismodified. The split sleeve can be mounted in a position so that acylindrical part of the bolt only engages the split sleeve when thetravel becomes greater than the normal setting, the engagement of theparts causing friction to be set up, which aids the main spring to bringthe mass of the bolt to rest. The spring at this point, being undermaximum compression, then forces the bolt forward, therefore disengagingthe cylindrical part of the bolt from the split sleeve, and the bolt isthereafter free to move forward in the usual manner.

In order that the invention may be more fully understood reference ismade to the accompanying drawings wherein a preferred embodiment of theinvention is shown, and wherein:

Fig. 1 is a longitudinal sectional elevation of an automatic firearm,showing the bolt in the cooked position,

Fig. 2 is a cross section taken on the line 22 in Fig. 1 showing theform of braking device,

Fig. 2a is a View similar to Fig. 2, showing a modified form ofthebraking device.

Fig, 3 shows the bolt at the end of its forward movement at the time offiring.

Fig. 3a is a longitudinal section of the rear end of the bolt casing,showing another form of braking device.

Fig. 4 shows in part section a modified form of the bolt.

Referring to the drawings the bolt and its components A reciprocatewithin the casing B, and in its rearward motion compresses the recoilspring C which latter has an abutment on a flange 9 of the firing pinbody 2 and on the end cap D. The bolt A in the form shown has threeprincipal parts, the forward or slipper portion l engaging the interiorof the cylindrical casing B, an inner concentric firing pin body 2, andan intermediate sleeve 3. These three parts are each capable of relativeaxial movement or of combined movement. Said sleeve 3 has rear andforward parts of differing diameters providing a shoulder 4, saidshoulder adapted to engage the terminal rim of bolt part I and enablesleeve 3 to have its fore part 3a internal of bolt part I whilst itsrear part 3b is in external alignment with the rear outer extremity ofthe shoulder 5. The sleeve part 3a is flanged at B and carries theforward end of spring 'i which abuts rearward upon shoulder 8 of thefiring pin body 2 The firing pin body 2 has a flange 9 which constitutesone abutment for the recoil spring C, the other aboutment being therecess H] in the end cap D. The braking device consists of a continuousor discontinuous ring 12, see Fig. 2, having a flanged head l3, theouter flange adapted to engage the rear end of the casing B, said ringhaving a small permissible axial movement between the casing rim B andthe inside rear face of cap D. The ring i2 is mounted externally of therecoil spring C and is formed with a series of axially cut leaves I4,each of a section tapering as at l5 forward, the said forwardextremities being flared outwardly as at H5.

The bolt is positioned in Fig. 1 in the cooked position, the sear Eengaging the shoulder F formed upon the foreface of the boltA. The searin the known manner is under control of the trigger G in conjunctionwith a fire selection device H. Part 2 situated within bolt A carriesthe firing pin J.

The operation of the invention is as follows:

Referring to Fig. 3, the bolt A is shown in its firing position, thefore part engaging the breech of barrel K. Under this condition therecoil spring C is fully extended, and the firing pin J in its operativeposition, the base of the inner firing pin body 2 contacting the rearwall of the bolt socket with the spring '5 extended. As a result of theexplosive charge being initiated by the firing pin J the bolt A asa'whole then starts to move carrying the sleeve 3 compressing the recoilspring C, until the sleeve part 31) enters the flared throat H5 of thespring leaves M of the brake ring 42. The said spring leaves press uponthe sleeve 3 and exert therefore a continuously increasing frictionalresistance to the passage rearward of the bolt as a whole, in additionto the increasing resistance of the recoil spring 0.

Finally the motion of the bolt is arrested and under urge of the recoilspring C the bolt A comprising the fore part, sleeve 3 and firing pinbody 2 is forced outward again for a further operation to fire unlessthe said bolt is restrained in its longitudinal motion by the sear undertrigger and fire control as shown in Fig. 1.

During the forward movement of the bolt as a whole the firing pin bodyabuts upon the rear face of the bolt A and the sleeve 3 may haverelative motion but drag behind by reason of the frictional grip of thebrake [2 upon its rear periphery. Should this happen the flange abutment9 engages the shoulder 4 of the sleeve 3 with momentum and causes thesleeve to disengage and move into the position shown in Fig. 1, thespring I assisting this operation.

Under all conditions the force of the recoil spring 0 is sufiicient toovercome any momentum of the composite bolt A, as well as the frictionof the braking ring lz'upon the sleeve 3.

With weak ammunition the rearward travel of the bolt against the recoilspring may not be sufficient for the bolt parts to engage the brake,

4 and the bolt comes to a position of limit of travel as shown inFig. 1. The brake ring l2 may be either a continuous or discontinuousring, the discontinuous form shown in Fig. 2a, however, enabling thebrake fitting to be applied to a variety of weapons ofthe same class,having small divergencies of diameter of the bolt race casing B.

Again, in other forms of bolt construction, for instance where thefiring pin is a solid entity on the face of the bolt, the firing pinbody 2 and independent sleeve 3 are dispensed with, and the rear of thebolt formed to engage the braking device, see Fig. 4.

In order to provide means of easing any tendency to grip between thesleeve 3 and the braking device l2 the sleeve 3 may be provided with aninclined slot 20 into which the pin 2| enters, said pin convenientlybeing the stem of the conventional cocking handle. The interengagementof the said pin 2! with the walls of the slot 20 causes slight rotationof the sleeve 3. This feature is of importance should grit or otheradventitious matter be lodged in the split sleeve and tend to create abinding action between the engaged parts. The effect of this turningmovement is to assist disengagement and transfer any grit allowing it toescape through the nearest interstice between the component leaves ofthe brake ring.

. In weapons having a rectangular form of bolt block, flat frictionbraking pads can be fittedinstead of cylindrical parts. Again, the splitring I2 above referred to can be dispensed with by forming the saidringasa part of the bolt race casing or wall of breech block, as shownin Fig. 3a.

By the means above described the 'rateoffire is brought under controldespite variation in the explosive energy of the ammunition used andcontinuous firing with weak ammunition eliminated. In such latterconnection the shoulder F on bolt A may, if required, be placed furtherrearward, the sear E travelling in a groove out in the bolt (-not shown)until the shoulder is reached. r

I claim:

In an automatic firearm, the combination of a reciprocatory breech bolt,a recoil spring therefor, a friction brake in telescopic relation withthe bolt and engageable frictionally therewith during the recoilthereof, and means for imparting relative rotation between saidboltand'friction brake during reciprocation of said bolt.

GEORGE WILLIAM PATCHETT.

REFERENCES CITED The following. references are of record in the file ofthis patent:

UNITED STATES PATENTS Great Britain Nov. 10;, 1927

